Note: Descriptions are shown in the official language in which they were submitted.
WO 96J01381 PGT/US95/08251 ,
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FIVE-SPEED AUTOMATIC TRANSMISSION
The present invent~.on relates
generally to automatic transmissions for
vehicles and, more particularly, to a five-speed
automatic transmission for as automotive
vehicle.
A conventional automatic transmission
includes a hydrodynamic torque converter to
transfer engine torque from an engine crankshaft
to a rotatable input member of the transmission
through fluid-flow forces. The transmission
also includes frictional units, typically
referred to as clutches, which couple the
rotatable input member to one or more members of
a planetary gearset. Other frictional units,
typically referred to as brakes. hold one or
more members of the planetary gearset stationary
during the flow of power. Such transmissions
also typically provide for one or more planetary
gearsets~in order to provide various ratios of
torque and to ensure that the available torque
and the respective tractive power demand are
matched to each other.
An example of an automatic
transmission having a plurality of planetary
gearsets is a ZF five-speed automatic
transmission (5 8P 30) commercially available
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from Zahnradfabrik Friedrichshafen AG of Germany
and found on the 1994 Brv 540i vehicles. The ZF
five-speed automatic transmission includes a
torque converter with a lock-up clutch, three
drive clutch assemblies. three brake assemblies,
and three planetary gearsets.
One disadvantage of the above ZF five-
speed automatic transau.ssion is that the
arrangement of the planetary gearsets provides
higher losses of efficiency is fifth gear
because all three gearsets are loaded. Another
disadvantage of the ZF five~,speed automatic
transmission is that it is more difficult with
good planetary -gearset design to provide a 0.75
overdrive ratio and good rat"~p spacing.
It is, therefore, one object of the
present invention to provide a five-speed
automatic transmission for an automotive
vehicle.
It is another object of the present
invention to provide a five-speed automatic
transmission that has a plurality of planetary
gearsets arranged to provide all ratio steps of
small to medium magnitude.
It is yet another object of the
present invention to provide a five-speed
automatic transmission that has a plurality of -
planetary gearsets arranged to provide a 0.75
overdrive ratio.
~ It is still another object of the
present invention to provide a five-speed
automatic transmission that minimizes losses of
efficiency in fifth gear.
To achieve the foregoing objects, the
present invention is a five-speed automatic
transmission for a vehicle including a
transmission housing, an input member, an output
WO 96!01381 . PCT/OS95/08251
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member, a plurality of planetary gearsets for
changing a ratio of torque between the input
member and the output member, a plurality of
clutch assemblies to selectively couple the
input member to predetermined gears of the
planetary gearsets, a plurality of brake
assemblies to selectively couple predetermined -
gears of the plaaetary gearsets to the
transmission housing, and means for allowing the
output member and a planetary carrier from one
of the planetary gearsets, an annulus gear from
another of the planetary gea'$rsets and a sun gear
from another of the planetary gearsets to rotate
simultaneously.
One advantage of tf~ce present invention
is that a five-speed automatic transmission is
provided for an automotive vehicle. Still
aaothe~ advantage of the present invention is
that the five-speed-automatic transmission has a
plurality of planetary gearsets arranged to
provide good ratio spacing of small to medium
magnitude, especially between first and second
gears. A further advantage of the present
invention is that the five-speed automatic
transmission provides a unique arrangement of
planetary gearsets to achieve a 0.75 overdrive
ratio in fifth gear. Still a'further advantage
of the present invention is.that the five-speed
automatic transmission minimizes losses of
efficiency in fifth gear by loading only one
planetary gearset.
Other objects, features and advantages
of the present invention will be readily
appreciated as .the same becomes better
understood after reading the subsequent
description taken in conjunction with
accompanying drawings.
CA 02194356 2005-09-28
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FIGS. 1A and 1B are a cross-sectional view of a five-speed automatic
transmission according to the present invention.
FIG. 2 is a cross-sectional schematic view of the five-speed automatic
S transmission of FIGS. 1A and 1B.
FIG. 3 is a chart of gears, gear ratio and clutches and brakes engaged
for the five-speed automatic transmission of FIG. 2 when used as a five-speed
overdrive.
Referring to FIGS. 1A and 1B, a cross-sectional view of a five-speed
automatic transmission, according to the present invention, is partially shown
at 10. The five-speed automatic transmission 10 is adapted for use in a
vehicle
(not shown) such as an automotive vehicle. The five-speed automatic
transmission 10 is similar to the four-speed automatic transmission disclosed
in U.S. Pat. No. 4,875,391 except to that specifically illustrated and
described
1 S herein.
The five-speed automatic transmission 10 includes a transmission
housing 12 for enclosing a torque converter assembly (not shown), an input
member 14, an output member 16, a mufti-clutch and brake assembly,
generally indicated at 18, and a gear assembly generally indicated at 20. 'The
transmission housing 12 is stationary relative to the rotatable input member
14, output member 16 and gear assembly 20. Power is transmitted from a
rotating crankshaft (not shown) of an engine (not shown) to the torque
converter assembly, in turn, to the rotatable input member 14.
The mufti-clutch and brake assembly 18 allows predetermined gears
2S within the gear
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assembly 20 to be selectively engaged and
disengaged from either the input member 14 or
the transmission housing 12. Near the input
side of the transmission 10, the mufti-clutch
aad brake assembly 18 includes an underdrive
clutch assembly 22. (applied in first, second,
third sad fourth gears), an overdrive clutch
assembly 24 (applied in fourth and fifth gears)
sad a reverse clutch assembly 26 (applied in
reverse gear). Near the output side of the
traasmission 10, the mufti-clutch and brake
assembly l8 includes a three~five (35) brake
assembly 28 (applied in third and fifth gears),
a low/reverse brake assembly 30 (applied in
first and reverse gears) end's second brake '.
assembly 32 (applied in second gear). The
mufti-clutch and brake assembly 18 also includes
an input retainer hub 33 splined to the input
member 14 and an input retainer 34 splined to
the iaput clutch retainer hub 33.
The uaderdrive clutch assembly 22
includes a plurality of axially spaced annular
plates 22a and a plurality of axially spaced
annular discs 22b which are alternated between
the plates 22a and when the underdrive clutch
assembly 22 is not applied, these plates 22a and
discs 22b are free to move or rotate relative to
each other. The plates 22a are mounted to the
input retainer 34 and the discs 22b are mounted
to an underdrive hub 36. The underdrive hub 36
is operatively connected to a rotatable gear
shaft 37 of the gear assembly 20.
The overdrive clutch assembly 24
includes a plurality of axially spaced annular
plates 24a aad a plurality of axially spaced
annular discs 24b. The plates 24a and discs 24b
are similar to those of the underdrive clutch
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assembly 22. The plates 24a are mounted to the
input retainer 34 and the discs 24b are mounted
to an overdrive hub 38 operatively supported
about the gear shaft 37 of the gear assembly 20.
The reverse clutch assembly 26
includes a plurality of axially spaced angular
plates 26a and a plurality of axially spaced
annular discs 26b. The plates 26a and discs 26b
are similar to those of the underdrive clutch
assembly 22. The plates 26a are mounted to the
input retainer 34 and the discs 26b are mouated
to a reverse hub 40 operatively connected to the
gear assembly 20. It should be appreciated that
the clutch assemblies 22, 24 aad 26 are applied
by fluid actuating devices 4'~ and 42 similar to
that in U.S. Patent No. 4,875,391.
The three/five brake.assembly 28
iacludes a plurality of axially spaced angular
plates 28a and a plurality of axially spaced
annular discs 28b. The plates 28a and discs 28b
are similar to those of the underdrive clutch%
assembly 22. The plates 28a are mounted to the
transmission housing 12 and the discs 28b are
mounted to a connecting member 43 connected to
the reverse hub 40.
The low/reverse brake assembly 30
includes a plurality of axially spaced annular
plates 30a and a plurality of axially spaced
annular,discs 30b. The plates 30a and discs 30b
are similar to those of the underdrive clutch
assembly 22. The plates 30a are mounted to a
connecting member 44 connected to the
transmission housing 12 and the discs 30b are ,
mounted to a connecting member 45 of the gear
assembly 20 to be described further herein.
The second brake assembly 32 includes
a plurality of axially spaced annular plates 32a
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PCT/US95/08251
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and a plurality of axially spaced annular discs
32b. The plates 32a and discs 32b are similar
to those of the underdrive clutch assembly 22.
The plates 32a are mounted to the transmission
housing 12 and the discs 32b are mounted to an
annulus gear 72 of the gear assembly 20 to be
described further herein. It should be -
appreciated that the brake assemblies 28, 30 and
32 are applied by fluid actuating devices 46, 47
and 48, respectively.
The gear assembly 20 includes a frost
or first planetary gearset, generally indicated
at 49~ an axially spaced intermediate or second
planetary gearset, generally indicated at 50,
and an axially spaced rear oi'~third planetary
gearset, generally indicated at 51. The first
planetary gearset 49 includes a first sun gear
52 at its center. The first sun gear 52 is
connected to the reverse hub 40. The first
planetary gearset 49 also includes a first
planetary carrier 54 having a plurality of '
circumferentially spaced first pinion gears 55
to engage the first sun gear 52. The first
planetary carrier 54 is spline connected to the
overdrive hub 38. The first planetary gearset
49 further includes a first annulus gear 56
disposed about the first planetary carrier 54
and engages the first pinion gears 55. The
ratio of.the number of teeth on the sun gear to
the number of teeth on the annulus gear in this
example is 3.00. The first annulus gear 56 is
connected to a connecting member 57 of the gear
assembly 20.
The intermediate or second planetary
gearset 50 includes a second sun gear 58 at its
center Which is spline connected to the gear
shaft 37. The second planetary gearset 50 also
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includes a second planetary carrier 60 having a
plurality of circumferentially spaced second
pinion gears 61 to engage the second sun gear
58. The second planetary carrier 60 is
connected to the connecting member 57 which is,
in turn, connected to the first annulus gear 56.
The second planetary carrier 60 is also spline
connected to the output member 16. The second
planetary gearset 50 further includes a second
annulus gear 62 disposed about the second
planetary carrier 60 and engages the second
pinion gears 61. The ratio o~ the number of
teeth on the sun gear to the number of teeth on
the annulus gear in this example is 2.55. The
second annulus gear 62 is con~iected to a
connecting member 64 which is, in turn,
connected to the first planetary carrier 54 and -
connecting member 45.
The rear or third planetary gearset 51
includes a third sun gear 66 at its center which
is spline connected to the output member 16 of '
the transmission 10. The third planetary
gearset 51 also includes a third planetary
carrier 68 having a plurality of
circumferentially spaced third pinion gears 69
to engage the third sun gear 66. The third
planetary carrier 68 is spline connected to a
connecting member 70 which is, in turn,
connected.to the connecting member 45. The
third planetary gearset 51 further includes a
third annulus gear 72 disposed about the third
planetary carrier 68 and engages the third
pinion gears 69. The ratio of the number of
teeth on the sun gear to the number of teeth on
the annulus gear in this example is 1.55.
Referring to FIG. 2, a cross-sectional
schematic view of the transmission 10 is
WO 96/01381 b pCT/US95108251
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illustrated. In operation, the input member 14
of the transmission 10 rotates due to torque
being transferred from the rotating crankshaft
of the engine and through the torque converter
assembly to the input member 14. The input
retainer hub 33 and input retainer 34 also
rotate with the input member 14 due to their
connectioa. The plates 22a, 24a, 26a also
rotate with the input retainer 34 due to the
connection between them.
When the underdrive clutch assembly 22
is applied, the rotating plates 22a and discs
22b of the underdrive clutch assembly 22 engage
each other aad a frictional force is produced
between the plates 22a and d~~cs 22b. Because
the iaput retainer 34 and plates 22a are
rotating, the frictional force causes the discs
22b and uaderdrive hub 36 to rotate, in turn,
rotating the gear shaft 37 and second sun gear
58 of the second planetary gearset 50.
When the overdrive clutch assembly 24
is applied, the rotating plates 24a and discs
24b of the overdrive clutch assembly 24 engage
each other and a frictional force is produced
between the plates 24a and discs 24b. Because
the input retainer 34 and plates 24a are
rotating, the frictional force causes the discs
24b and overdrive hub 38 to rotate, in turn,
rotating, the first planetary carrier 54, connect-
ing member 64, second annulus gear 62, connect-
ing member 70 and third planetary carrier 68.
When the reverse clutch assembly 26 is
applied, the rotating plates 26a and discs 26b
of the reverse clutch assembly 26 engage each
other and a frictional force is produced between
the plates 26a and discs 26b. Because the input
retainer 34 and plates 26a are rotating, the
WO 96/01381 . PCT/(TS95I08251
' ~.~ 945 ~
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frictional force causes the discs 26b and
reverse hub 40 to rotate, in turn, rotating the
first sun gear 52.
When the three/five brake assembly 28
is applied, the plates 28a and discs 28b of the
three/five brake assembly 28 engage each other
and a frictional force ie produced between the
plates 28a and discs 28b. Because the plates
28a do not rotate or are stationary, as they are
connected to the transmission housing 12, the
frictional force holds the discs 28b, connecting
member 43 and reverse hub 40r~stationary, in
turn, holding the first sun gear 52 stationary.
When the low/reverse brake assembly 30
is applied, the plates 30a ai~t~i discs 30b of the
low/reverse brake assembly 30 engage each other
and a frictional force is produced between the
plates 30a and discs 30b. Because the plates
30a are stationary, as they are connected by the
connecting member 44 to the transmission housing
12, the frictional force holds the discs 30b
stationary, in turn, holding the connecting
member 45, connecting member 70, connecting
member 64, first planetary carrier 54, second
annulus gear 62 and third planetary carrier 68
stationary.
When the second brake assembly 32 is
applied, the plates 32a and discs 32b of the
second brake assembly 32 engage each other and a
frictional force is produced between the plates
32a and discs 32b. Because the plates 32a are .
stationary, as they are connected to the
transmission housing 12, the frictional force
holds the discs 32b stationary, in turn, holding
the third annulus gear 72 stationary.
Referring to FIGS: 2 and 3, when the
transmission 10 is desired to operate in first
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gear, the underdrive clutch assembly 22 and
low/reverse brake assembly 30 are applied. This
causes the second sun gear 58 to rotate and the
second annulus gear 62 to be held stationary.
As a result, rotation of the second sun gear 58
causes rotation of the second pinion gears 61
and the second planetary carrier 60. Because
the output member 16 is connected to the second
planetary carrier 60, rotation of the second
planetary carrier 60 causes the output member 16
to rotate. This arrangement of the gear
assembly 20 produces a geax~,ratio of 3.55.
When the transmission 10 is desired to
operate in second gear, the underdrive clutch
assembly 22 and the second b~,ake assembly 32~are
applied. This causes the second sun gear 58 to
rotate and the third annulus gear 72 to be held
stationary. By holding the third annulus gear
72 stationary, the third planetary carrier 68
and second annulus gear 62 rotate. As a result,
the second planetary carrier 60, third sun gear
66 and output member 16 rotate at a greater r.p.m.
than in first gear. This arrangement of the
gear assembly 20 produces a gear ratio of 2.55.
When the transmission 10 is desired to
operate in third gear, the underdrive clutch
assembly 22 and the three/five brake assembly 28
are applied. This causes the second sun gear 58
to rotate and the first sun gear 52 to be held
stationary. As a result, rotation of the second
sun gear 58 causes the second planetary carrier
60 and first annulus gear 56 to rotate. By
holding the first sun gear 52 stationary, the
first pinion gears 55 and first planetary
carrier 54 and second annulus gear 62 are made
to rotate. As a result, the second planetary
carrier 60, first annulus gear 56 and output
WO 96/01381 . ~ PGT/US95/08251
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member 16 rotate at a greater r.p.m. than in
second gear. This arrangement of the gear
assembly 20 produces a gear ratio of 1.64.
When the transmission 10 is desired to
operate in fourth gear, the underdrive clutch
assembly 22 and the overdrive clutch assembly 24
are applied. This causes the second sun gear 58
and second annulus gear 62 to rotate at the same
speed. This causes the second planetary carrier
60 and output member 16 to also rotate at the
same speed. This arrangement of the gear
assembly 20 produces a gear patio of 1.00.
When the transmission 10 is desired to
operate in fifth gear, the overdrive clutch
assembly 24 and the three/fi~tFe brake assembly
are applied. This causes the first planetary
carrier 54 to rotate and the first sun gear 52
to be held stationary. As a result, rotation of
the first planetary carrier 54 causes the first
annulus gear 56 and output member 16 to rotate
at a higher r.p.m. than in fourth gear. This
arrangement of the gear assembly-20 produces a
gear ratio of 0.75.
When the transmission 10 is desired to
operate in reverse gear, the reverse clutch
assembly 26 and low/reverse brake assembly 30
are applied. This causes the first sun gear 52
to rotate and the first planetary carrier 54 to
be held stationary. As a result, the first sun
gear 52 rotates the first pinion gears 55 which,
in turn, rotate the first annulus gear 54 .
backwards. Rotation of the first annulus gear
56 causes the second planetary carrier 60 to
rotate which, in turn, causes rotation of the
output member 16 in a direction opposite to the
other gear positions. This arrangement of the
gear assembly 20 produces a gear ratio of -3.00.
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Accordingly, the five-speed automatic
transmission 10 has a unique arrangement of the
planetary gearsets 46, 48 and 50 to achieve a
0.75 overdrive ratio in fifth gear. The unique
arrangement of the planetary gearsets 46, 48 and
50 results in ratio steps of small to medium
magnitude.
The present invention has been
described in an illustrative maaaer. It is to
be understood that the terminology which has
been used is intended to be in the nature of
words of description rather ~haa of limitation.
Many modifications and variations of
the present invention are possible in light of
the above teachings. Therefb~e, within the .,
scope of the appended claims, tie present
invention may be practiced other than as
specifically described.
z
